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DARWIND5 wind turbine improves on an old design

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October 30, 2012

Canadian startup Harvistor has tested its DARWIND5 vertical axis wind turbine and says it ...

Canadian startup Harvistor has tested its DARWIND5 vertical axis wind turbine and says it can deliver more power than current models

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Ontario, Canada has carved out a niche for itself as a hub of green technology. One of the latest clean tech innovations to come out of that province is DARWIND5, a vertical axis wind turbine (VAWT). Designed by Harvistor, it comes with a promise of more oomph than existing models for small-scale wind power generation. According to the company, recent tests showed that its technology can achieve 35 percent more kilowatt hours per year than current VAWTs for the same sweep area, besides operating at 25 percent lower heights than similarly priced market leaders.

Harvistor says it approached the DARWIND5 design like F1 racing, with performance boosted by a new type of rotor blade telemetry and geometry. This translates into new airfoil shapes, which allow the rotor system to completely avoid power-robbing dynamic stall, a reaction that occurs when airfoils rapidly change the angle of attack.

Individually, each rotor has a longer power stroke than previously thought possible because the new airfoil shape flies upside down and right side up during key parts of rotation, like a stunt airplane doing a full loop. During rotation, the lift forces change twice from moving away from the shaft to moving toward the shaft, making for the longer stroke. All of these forces occur on the windward side of the turbine – any turbulence exits on the leeward side, where it doesn't affect the turbine. This avoids individual torque peaks, which are a major cause of wind turbine breakdowns

With nameplate power (capacity under ideal conditions) ranging between 500 watts and 1.5 kilowatts in a 1.2-meter (3.9-ft) working diameter, DARWIND5 operates at a speed that ranges between 4 m (13.2 ft) and 24 m (78.7 ft) per second. It doesn’t need a brake because it self-regulates the top RPM – until now, unregulated top speeds have been a problem with VAWT design. A cantilevered tilt mount design reportedly makes cleaning and repairing an easy task, allowing it to be done anytime without power production loss or delays.

Harvistor’s design is an improvement on the Darrieus design, also known as the “eggbeater”

DARWIND5 is mounted 25 to 35 percent lower than the nacelle of horizontal axis wind turbines. Being lower to the ground is better, claims Harvistor, because it does not affect property values and makes the turbine more aesthetically pleasing, which should assuage the fears of people who find wind turbines an eyesore.

The turbine was based on the Darrieus design, also known as the “eggbeater." It expanded on previous efforts carried out by the National Research Council Canada and Ministry of Natural Resources as well as Sandia National Labs. Sandia's pioneering work in 1974 (which carries on to this date) resulted in the first commercial Darrieus systems. These were produced by Flowind and used in California by PG&E and Southern California Edison between 1984 and 1996. DARWIND5 improves Flowind’s design by making it more reliable. The design features lower and more evenly placed rotor blade loads, thanks to less vibration.

The project was developed and tuned on supercomputer 3D CFD software and used a performance simulation tool called Beater. The tests carried out in June of this year validated DARWIND5’s performance, meaning the Beater tool can now be used to upgrade DARWIND5 turbines into the MW class. The field test height was 3.5 meters (11.48 ft) and was performed in stationary and moving set-ups.

Harvistor says its ownership of the rotor blade and engineer design gives it a competitive edge. The company has submitted a project to KickStarter that was pending approval at the time of writing this article.

Video of the June, 2012 field test can be viewed below (although disregard the voice over saying the date is 2011).

UPDATE: The company now informs us that its crowd-funding project will be based through the Pozible website, and should be live as of November 15th.

Source: Harvistor

About the Author
Antonio Pasolini Brazilian-Italian Antonio Pasolini graduated in journalism in Brazil before heading out to London for an MA in film and television studies. He fell in love with the city and spent 13 years there as a film reviewer before settling back in Brazil. Antonio's passion for green issues - and the outdoors - eventually got the best of him and since 2007 he's been writing about alternative energy, sustainability and new technology.   All articles by Antonio Pasolini
11 Comments

Something about this doesn't add up. They claim this was developed on a supercomputer, yet they need funding through Kickstarter. They claim lower is better for aesthetic reasons, but in reality, higher is better because wind speed and power density increases with altitude.

Gadgeteer
30th October, 2012 @ 04:34 pm PDT

That seems normal to me. Most kickstarter projects already have a prototype before they launch through kickstarter. The kickstarter money is used to work out kinks and produce in volume, not to design the product.

>They claim lower is better for aesthetic reasons, but in reality, higher is better because wind speed and power density increases with altitude.

Right, that isn't contradictory.

Daishi
30th October, 2012 @ 05:46 pm PDT

I think one man's supercomputer is another man's ordinary computer. Also, running simulations on super computers is probably not that expensive assuming you've set up the simulation(s) before hand all ready to run. In that case the per hour charges are only for the actual scenario runs. The amount of the kickstarter is not specified. If they were looking for a couple of thousand dollars I'd agree with Gadgeteer that it seems a bit odd, but they could be looking for 10s/100s of thousands.

Higher altitude has more wind (in general) but the point is you can generate useful power at a lower altitude. The Darwind5 is aimed at small / residential power generation (maybe small farm / semi-rural type of thing) not national power grid. In those instances aesthetics and practicality are more important.

Scion
30th October, 2012 @ 05:47 pm PDT

Anyone who moves their aeroturbine closer to the ground is removing it from the resource..

It has the same effect as putting a shade over your solar panels.

nutcase
30th October, 2012 @ 07:02 pm PDT

What's the proposed price point?

Joel Detrow
30th October, 2012 @ 07:19 pm PDT

Higher is also better because sand, dirt, and grit tend to be nearer the ground. The thrust bearing for VAWTs is at the bottom of the rotor. When that fills with dirt, the rotor becomes much less efficient. One of the design criteria should be ease of removal and replacement of the thrust bearing.

dchall8
30th October, 2012 @ 07:21 pm PDT

It can't make the power they claim and certainly not low down out of the wind power source.

jerryd
31st October, 2012 @ 08:40 pm PDT

"the wind power source"? big, fancy name for the sun, right?

most wind turbines automatically feather once the wind exceeds their design speed, which is surprisingly low (long blades develop very high tip speeds at low rpm), so there's a very specific upper limit to how much is better.

as to the article, the claimed 35% improvement sounds good, but in reality, wind turbines only produce about 15% of their plated capacity; moving the bar up to 20% still means they're wasting 80% of their capital investment's potential.

Yevgenyi Nikolas Gorbachev
1st November, 2012 @ 07:06 am PDT

"the wind power source"? big, fancy name for the sun, right?

most wind turbines automatically feather once the wind exceeds their design speed, which is surprisingly low (long blades develop very high tip speeds at low rpm), so there's a very specific upper limit to how much is better.

as to the article, the claimed 35% improvement sounds good, but in reality, wind turbines only produce about 15% of their plated capacity; moving the bar up to 20% still means they're wasting 80% of their capital investment's potential.

Yevgenyi Nikolas Gorbachev
1st November, 2012 @ 07:08 am PDT

If this Unit was Placed in Mountain regions with strong up and down draft winds this is where this Unit will be superior over the standard models that can not capture up and down, or side way winds. Testing it on the flat open plane rather then mountain tops perhaps does not show what it really can do.

Trent Nicolajsen
3rd November, 2012 @ 02:44 pm PDT

Good discussion here.

One of the issues in my area is aesthetics, especially for small residential installations.

A variable height tower may do two things

1. remove the turbine from strong winds. Long blade turbines change pitch to maintain reasonable tip speed as mentioned above. that may be a challenge for this design, not known.

2. deploying the turbine only when wind energy is available may be one answer to the community as they object to small local wind turbines.

Jim Ellsworth
6th November, 2012 @ 01:46 am PST
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